Untitled Flashcards Set

 Chapter 3: Chemical Formulas and Composition  

1. How do you determine the empirical formula of a compound?  

   - Convert the given mass or percentage of each element to moles.  

   - Divide by the smallest number of moles to get a simple whole-number ratio.  

   - If needed, multiply by a factor to obtain whole numbers.  

2. How do you convert an empirical formula to a molecular formula?  

   - Determine the molar mass of the empirical formula.  

   - Divide the given molar mass of the compound by the empirical formula mass.  

   - Multiply each subscript in the empirical formula by the obtained factor.  

3. How do you calculate the percent composition of an element in a compound?  

   - Use the formula:  

     \text{Percent composition} = \left(\frac{\text{Mass of element in one mole of compound}}{\text{Molar mass of compound}}\right) \times 100

 Chapter 4: Chemical Reactions and Stoichiometry  

4. What are the different types of chemical reactions and how are they identified?  

   - Synthesis: Two or more substances combine to form one product.  

   - Decomposition: A single compound breaks down into simpler substances.  

   - Single Displacement: An element replaces another in a compound.  

   - Double Displacement: Two compounds exchange ions.  

   - Combustion: A hydrocarbon reacts with oxygen to form CO₂ and H₂O.  

5. How do you balance a chemical reaction?  

   - Adjust coefficients to ensure the same number of atoms for each element on both sides.  

6. How do you perform stoichiometric calculations for reactants and products?  

   - Convert given mass to moles.  

   - Use the balanced equation to find the mole ratio.  

   - Convert moles back to mass if needed.  

7. How do you determine the limiting reactant, theoretical yield, and percent yield?  

   - Limiting Reactant: Compare the mole ratio of reactants. The one that produces the least product is limiting.  

   - Theoretical Yield: Use the limiting reactant to calculate the expected amount of product.  

   - Percent Yield:  

     \text{Percent Yield} = \left(\frac{\text{Actual Yield}}{\text{Theoretical Yield}}\right) \times 100

8. How do you predict a combustion reaction?  

   - A hydrocarbon reacts with O₂, producing CO₂ and H₂O.  

9. Why does potassium (K) react more vigorously with water than lithium (Li)?  

   - Potassium has a lower ionization energy and larger atomic radius, making it more reactive.  

10. How do halogens react with other elements?  

   - Halogens undergo displacement reactions, where a more reactive halogen replaces a less reactive one in a compound.  

 Chapter 5: Solutions and Aqueous Reactions  

11. What are solute, solvent, and solution?  

   - Solute: The substance dissolved in a solution.  

   - Solvent: The substance that dissolves the solute.  

   - Solution: A homogeneous mixture of solute and solvent.  

12. How do you differentiate between dilute and concentrated solutions?  

   - Dilute: Low amount of solute per solvent.  

   - Concentrated: High amount of solute per solvent.  

13. How do you calculate molarity (M)?  

   - 

     M = \frac{\text{Moles of solute}}{\text{Liters of solution}}

14. How is molarity used in solution stoichiometry?  

   - It allows conversion between volume and moles using  

     \text{Moles} = M \times \text{Volume (L)}

15. What is the difference between an electrolyte and a non-electrolyte solution?  

   - Electrolytes: Conduct electricity (strong acids, bases, and salts).  

   - Non-electrolytes: Do not conduct electricity (covalent compounds like sugar).  

16. How do acids and bases behave in water, and how is pH calculated?  

   - Acids: Release H⁺ ions.  

   - Bases: Release OH⁻ ions.  

   - pH Calculation:  

     \text{pH} = -\log[\text{H}^+]

17. What are strong and weak electrolytes?  

   - Strong Electrolytes: Fully dissociate in water (e.g., NaCl, HCl).  

   - Weak Electrolytes: Partially dissociate (e.g., HF, CH₃COOH).  

18. How do you determine solubility of ionic compounds in water?  

   - Use solubility rules to determine if a compound dissolves or precipitates.  

19. What is a precipitation reaction, and how is it identified?  

   - A reaction where an insoluble solid (precipitate) forms from two aqueous solutions.  

20. How do you write total and net ionic equations?  

   - Total Ionic Equation: Shows all strong electrolytes as ions.  

   - Net Ionic Equation: Eliminates spectator ions, showing only species that participate.  

21. What are spectator ions?  

   - Ions that do not participate in the reaction and remain unchanged.  

22. What are acid-base and gas evolution reactions?  

   - Acid-Base Reaction: Acid reacts with a base to form water and a salt.  

   - Gas Evolution Reaction: A reaction that produces a gas as a product.  

23. Why is HCl a stronger acid than HF?  

   - HCl dissociates completely, while HF forms hydrogen bonds and only partially dissociates.  

24. What is acid-base titration, and how is the equivalence point determined?  

   - A technique to determine the concentration of an acid or base using a neutralization reaction.  

   - Equivalence Point: When moles of acid = moles of base.  

25. What are oxidation-reduction (redox) reactions?  

   - Reactions involving the transfer of electrons.  

26. How do you identify oxidizing and reducing agents?  

   - Oxidizing Agent: Gains electrons (is reduced).  

   - Reducing Agent: Loses electrons (is oxidized).  

27. How do you assign oxidation numbers?  

   - Use oxidation number rules (e.g., O = -2, H = +1 in most compounds).  

28. How do you determine which element can displace another in a reaction?  

   - Use the reactivity series: A more reactive element displaces a less reactive one.